Solitary fibrous tumor of the floor of the mouth: A rare entity in an uncommon site

Solitary fibrous tumours (SFTs) are rare mesenchymal neoplasms of fibroblastic origin. Intraoral involvement is uncommon, with occurrence in the floor of the mouth being particularly rare. We report the case of a 42-year-old man presenting with a slow-growing, well-circumscribed mass located on the left side of the floor of the mouth. Gross examination revealed an encapsulated, pink-greyish mass measuring 3.3 cm at its greatest dimension. Histologically, the tumour consisted of uniform spindle cells arranged in a patternless architecture within a variably collagenized stroma, associated with prominent thin-walled branching vessels. Immunohistochemical studies demonstrated diffuse CD34 positivity and strong nuclear expression of STAT6, confirming the diagnosis of solitary fibrous tumour. This case highlights a rare intraoral presentation of SFT and underscores the importance of histopathological assessment supported by STAT6 immunohistochemistry for accurate diagnosis.